The origins of these linear virgae (virgae meaning a stripe of streak of color) are most likely caused by the draping of surface materials like material from Saturn's rings, passing comets, or co-orbital moons Helene and Polydeuces.

"The evidence preserved in the linear virgae has implications for the orbital evolution and impact processes within the Saturnian system," Patthoff said. "Plus, the interaction of Dione's surface and exogenic material has implications for its habitability and provides evidence for the delivery of ingredients that may contribute the habitably of ocean worlds in general."

Patthoff and Emily S. Martin of the Center for Earth and Planetary Studies at the National Air and Space Museum, Smithsonian Institution, are co-authors on a new paper "Mysterious linear features across Saturn's moon Dione" that appears in the journal Geophysical Research Letters. They studied images from NASA's Cassini spacecraft, which also revealed similar features on Saturn's moon Rhea.

Dione's linear virgae are generally long (10 to 100s of kilometers), narrow (less than 5 kilometers) and brighter than the surrounding terrains. The stripes are parallel, appear to overlie other features and are unaffected by topography, suggesting they are among the youngest surfaces on Dione.

"Their orientation, parallel to the equator, and linearity are unlike anything else we've seen in the Solar System," Patthoff said. "If they are caused by an exogenic source, that could be another means to bring new material to Dione. That material could have implications for the biological potential of Dione's subsurface ocean."

Patthoff's research was funded by a grant from NASA's Cassini Data Analysis Program.